arch/x86/include/asm/pvclock.h

   1 #ifndef _ASM_X86_PVCLOCK_H
   2 #define _ASM_X86_PVCLOCK_H
   3
   4 #include <linux/clocksource.h>
   5 #include <asm/pvclock-abi.h>
   6
   7 #ifdef CONFIG_KVM_GUEST
   8 extern struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void);
   9 #else
  10 static inline struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void)
  11 {
  12         return NULL;
  13 }
  14 #endif
  15
  16 /* some helper functions for xen and kvm pv clock sources */
  17 u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
  18 u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src);
  19 void pvclock_set_flags(u8 flags);
  20 unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
  21 void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
  22                             struct pvclock_vcpu_time_info *vcpu,
  23                             struct timespec *ts);
  24 void pvclock_resume(void);
  25
  26 void pvclock_touch_watchdogs(void);
  27
  28 static __always_inline
  29 unsigned pvclock_read_begin(const struct pvclock_vcpu_time_info *src)
  30 {
  31         unsigned version = src->version & ~1;
  32         /* Make sure that the version is read before the data. */
  33         virt_rmb();
  34         return version;
  35 }
  36
  37 static __always_inline
  38 bool pvclock_read_retry(const struct pvclock_vcpu_time_info *src,
  39                         unsigned version)
  40 {
  41         /* Make sure that the version is re-read after the data. */
  42         virt_rmb();
  43         return unlikely(version != src->version);
  44 }
  45
  46 /*
  47  * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
  48  * yielding a 64-bit result.
  49  */
  50 static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
  51 {
  52         u64 product;
  53 #ifdef __i386__
  54         u32 tmp1, tmp2;
  55 #else
  56         ulong tmp;
  57 #endif
  58
  59         if (shift < 0)
  60                 delta >>= -shift;
  61         else
  62                 delta <<= shift;
  63
  64 #ifdef __i386__
  65         __asm__ (
  66                 "mul  %5       ; "
  67                 "mov  %4,%%eax ; "
  68                 "mov  %%edx,%4 ; "
  69                 "mul  %5       ; "
  70                 "xor  %5,%5    ; "
  71                 "add  %4,%%eax ; "
  72                 "adc  %5,%%edx ; "
  73                 : "=A" (product), "=r" (tmp1), "=r" (tmp2)
  74                 : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
  75 #elif defined(__x86_64__)
  76         __asm__ (
  77                 "mulq %[mul_frac] ; shrd $32, %[hi], %[lo]"
  78                 : [lo]"=a"(product),
  79                   [hi]"=d"(tmp)
  80                 : "0"(delta),
  81                   [mul_frac]"rm"((u64)mul_frac));
  82 #else
  83 #error implement me!
  84 #endif
  85
  86         return product;
  87 }
  88
  89 static __always_inline
  90 u64 __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src, u64 tsc)
  91 {
  92         u64 delta = tsc - src->tsc_timestamp;
  93         u64 offset = pvclock_scale_delta(delta, src->tsc_to_system_mul,
  94                                              src->tsc_shift);
  95         return src->system_time + offset;
  96 }
  97
  98 struct pvclock_vsyscall_time_info {
  99         struct pvclock_vcpu_time_info pvti;
 100 } __attribute__((__aligned__(SMP_CACHE_BYTES)));
 101
 102 #define PVTI_SIZE sizeof(struct pvclock_vsyscall_time_info)
 103
 104 #endif /* _ASM_X86_PVCLOCK_H */